Unless you have a reason to learn the specifics of OSS or ALSA, I
recommend using PortAudio instead. It's cross-platform, has a very
easy to use API, and comes with lots of examples.
http://www.portaudio.com/
On Jul 5, 2005, at 4:22 PM, Craig Hughes wrote:
Hi Seth,
best place for these types of questions is on the gumstix-users
mailing list, which I'm cc'ing for followups. I'll answers in
between your questions below:
On Jul 2, 2005, at 2:48 PM, Seth Cameron wrote:
I've spent many days trying to make sense of the sound system for
AudioStix,
and unfortunately I'm stuck at this point.
I've learned what I could about OSS and the ioctl() calls that use
soundcard.h. I've had some success with this on documented features.
I believe the reason I am getting poor microphone recording
quality is that
the +20 dB mic boost is not on and not accessible using aumix (OSS).
That feature is accessible through aumix using the -i "input gain"
feature. -i 100 will turn on boost; -i 0 will turn it off. To set
the gain on MIC or LINEIN sources, use the MIC or LINEIN specific
gain options in aumix.
Other programs that appear related to our gumstix platform are:
ac97_codec.h / .c
pax-ac97.h / .c
pxa-audio.h / .c
I can see that some patches have been added that define MICBOOST,
etc., but
I have no idea how to use this code, nor can I find any
documentation or
sample code that make calls to functions found in these files.
aumix works :)
Do you know how to use these ac97 files?
Those files are part of the kernel drivers. You just need to load
the module, then you can use ioctls on /dev/dsp to control stuff.
Are they part of a library with an API?
They are part of the OSS AC97 driver.
What is loaded with modprobe pxa-97?
The pxa-ac97 driver.
Is there anywhere I can find some help or examples using the
UCB1400 with
Linux?
You don't really need to know normally that there's a usb1400 under
the hood -- you just interface with the OSS system, and it handles
the details for you. Lots of OSS samples out there -- download
more or less any linux audio app and you'll see how it accesses the
sound subsystem and communicates with it.
C
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